A free wing is a wing attached to an aircraft fuselage in a manner such that the wing is freely pivotally about its spanwise axis which is usually located forward of its aerodynamic center. This arrangement enables the wing to have an angle of attack which is determined solely by aerodynamic forces during flight and, therefore, subject only to aerodynamic pitching moments imposed by wing lift and drag. Rotation of the wing, without pilot intervention, induced by positive or negative vertical wind gusts striking the wing during flight, causes the angle of incidence or pitch between the wing and the aircraft fuselage to vary so that the wing presents a constant angle of attack to the relative wind enabling the aircraft to be essentially stall free during flight.
A free wing may be formed with elevons along the trailing edge thereof which are pilot controlled through appropriate linkages to enable the free wing to form the function that an elevator controlled surface performs in a fixed wing aircraft. The free wing is capable of maintaining its independent operation irrespective of upward or downward actuation of the elevons.
Whereas fixed wing aircraft routinely use flaps for take-off and landing, the inherent characteristics of the free wing prevent the use of flaps and therefore deprive the free wing aircraft with the ability to abruptly decelerate in a shortened roll-out after touchdown as otherwise occurs through the use of flaps deployed in a trailing edge up configuration in fixed wing aircraft. Since it is desirable to shorten the roll-out of an aircraft following touchdown, particularly in larger aircraft, a need therefore exists for shortening the roll-out of a free wing aircraft to a full stop.
U.S. Pat. No. 5,280,863 to Hugh Schmittle discloses a free wing aircraft wherein the free wing is lockable so that the aircraft can be converted between a free wing flight mode and a conventional, fixed wing aircraft flight mode. In the fixed wing flight mode, flaps may be provided along the trailing edge of the wing to perform their conventional function. However, there may be certain disadvantages to. providing a free wing aircraft with control mechanisms for selectively locking the free wing into a fixed wing configuration.
It is accordingly an object of the invention to utilize a free wing in a free wing aircraft as an air brake to abruptly decelerate the aircraft during roll-out after landing while the wing retains its free wing characteristics.